The present invention relates to a liquid crystal display substrate and a liquid crystal display device using an active matrix scheme and, more particularly, to a liquid crystal display substrate and a liquid crystal display device having a simplified circuit arrangement of a thin film transistor (to be referred to as a TFT) substrate.
FIG. 2 shows an equivalent circuit of a conventional liquid crystal display substrate using an active matrix scheme, and FIG. 3 shows the section of a main part of the conventional liquid crystal display substrate.
In FIGS. 2 and 3, reference numeral 21 denotes a liquid crystal display substrate arranged as follows. That is, a plurality of row terminals 24, common electrode terminals 23a and 23b, a plurality of column terminals 22, and common electrode terminals 23c and 23d are arranged on two adjacent sides of the liquid crystal display substrate 21, common electrode terminals 23e and 23f are arranged on one of the remaining sides, and pixel electrodes 36 and TFTs 37 for switching the pixel electrodes 36 are arranged in a matrix at cross points between lines 24a of the row terminals 24 and lines 22a of the column terminals 22. Reference numeral 25 denotes a first drive circuit substrate to which the plurality of row terminals 24 and the common electrode terminals 23a and 23b are connected. Reference numeral 26 denotes a second drive circuit substrate to which the plurality of column terminals 22 and the common electrode terminals 23c and 23d are connected. Reference numeral 27 denotes a third drive circuit substrate to which the common electrode terminals 23e and 23f are connected. Reference numerals 28 denote common electrode transfer pads arranged at the four corners of the liquid crystal display substrate 21. A display unit 29 is constituted by the large number of pixel electrodes 36 arranged in a matrix. In FIG. 3, a counter substrate 30 constitutes one of a pair of substrates constituting the liquid crystal display substrate 21, a TFT substrate 31 is arranged to interpose a liquid crystal 35 with the counter substrate 30 so as to oppose the counter substrate 30, and transparent electrodes 32 (to be referred to as counter electrodes) are formed on the counter substrate 30. The counter electrodes 32 of the counter substrate 30 are connected to the transfer pads 28 through silver paste portions 34, and the transfer pads 28 are connected to storage electrodes (not shown) on the TFT substrate 31.
As described above, the large number of square pixel electrodes 36 are formed on the TFT substrate 31 in a matrix, and each of the TFTs 37 is formed at one notched corner of each of the pixel electrodes 36. In addition, the lines 24a of the row terminals 24 and the lines 22a of the column terminals 22 are stacked and wired in a matrix to partition the pixel electrodes 36.
In the conventional liquid crystal display substrate with the above arrangement, the transparent electrodes 32 of the counter substrate 30 connected to the common electrode terminals 23a to 23f through the silver paste portions 34, the transfer pads 28, and the storage electrodes are driven as a common electrode.
The liquid crystal display substrate is driven as follows. As shown in FIG. 2, the row terminals 24 and the common electrode terminals 23a and 23b are connected to the first drive circuit substrate 25, the column terminals 22 and the common electrode terminals 23c and 23d are connected to the second drive circuit substrate 26, and the common electrode terminals 23e and 23f are connected to the third drive circuit substrate 27.
As described above, when the terminals are connected to the drive circuit substrates 25, 26, and 27, the common electrode is driven from the four corners of the liquid crystal display substrate 21, the transient response characteristics of a common electrode potential in the display unit 29 can be assured to obtain the display performance of the display unit 29.
In the above conventional liquid crystal display substrate, since the common electrode must be driven at the four corners of the liquid crystal display substrate to assure the display performance, the number of column data lines is small. As shown in FIG. 2, even when a data signal can be driven such that the liquid crystal display substrate is connected to one side of each of the drive circuit substrates, three drive circuit substrates, i.e., a row drive circuit substrate, a column (data) drive circuit substrate, and a common electrode drive circuit substrate must be connected to the liquid crystal display substrate.